Stealth Conversions began offering aftermarket vehicle speed sensors (VSS)
for engine swaps in 1991. The speed sensors are smog legal for engine swaps,
and have been issued CARB EO #D-371. Without a VSS, the Chevrolet Fuel Injected
engines will not run correctly, and they will not pass a smog test.

Basically, the VSS tells the ECM how fast the vehicle
is going. Most people think the VSS is only used for the lock-up torque converter.
The VSS is also used to control the EGR valve, the charcoal canister purge valve,
the electric cooling fans, idle speed, and air/fuel ratio. This is all explained
in the Chevrolet shop manuals.

It must be emphasized that the VSS is used
to control the idle speed when the vehicle is moving. Without the VSS, a vehicle
may have stalling problems under certain conditions. Needless to say, this is
dangerous. Raising the minimum idle speed with the adjusting screw can eliminate
stalling, but the engine will still not run optimally without a VSS.

A lot
of people think that running "closed loop" is best for fuel mileage. Closed
loop simply means that the oxygen sensor is being used to monitor the fuel/air
ratio. Some of the Chevrolet fuel-injected engines are programmed to run lean
under certain conditions (called "highway mode") to improve fuel mileage
during steady cruise conditions. Without a VSS, the engine computer (ECM) will
not get the correct signals to run the engine for best fuel mileage. There are
a lot of programs in the ECM that depend on the VSS. For best operation, the VSS
needs to be connected and functioning.

There
are four types of VSS signals required by the engine computer (ECM):

1.

The two-pulse (2000
pulses per mile) square wave (D.C. current or direct current) used on all TBI
engines through 1992, all computer-controlled-carbureted engines, and on 19851989
TPI engines.

A
40 pulse per driveshaft revolution speed sensor used on 1993 and newer trucks
with automatic transmission, 1994 and newer rear drive cars (Camaro, Corvette,
and Caprice) with the automatic transmission.

4.

A
17 tooth per driveshaft revolution speed sensor used on 19931997 LT1 engines
with the Borg-Warner 6-speed transmission. An 11 tooth reluctor ring is used on
1993 LT1 engines with the Borg-Warner wide ratio (3.35 First gear) 6-speed transmission.

PLEASE NOTE: Our manual goes into greater detail on this topic! We regret that we are unable to
enter into telephone or e-mail discussions concerning it, as we just cannot
spare the time!

Stealth Conversions
has several types of vehicle speed sensors designed for easy installation into
vehicles that were not equipped with vehicle speed sensors. All Stealth Conversions
VSS units have CARB EO numbers (#D-371)  they are smog legal for engine
swaps.

Part # 2PRS-TOY.Two-pulse for Toyota. Same as above, except for 22 mm metric threads, and .187 tang drive which fits Toyota transmissions and transfer cases.

5.

Part # 2X90. Dual output 90° angle drive. Use on Jaguars with electric speedometers. Allows connecting Jaguar XJ-S transducer on one end to operate Jaguar speedometer, and connecting two-pulse or four-pulse unit on other end for Chevrolet ECM. XJ-6 Jaguars must use tranducer from XJ-S.

3.

Part # 4PAC. Four-pulse sine wave.

Two other speed sensors we sell are pictured below (click links for details):

On the far right above is a 4-pulse integral VSS/speedometer sleeve. This VSS has provisions for using a standard speedometer cable and was used on 1990-1992 Police cars which had cable driven radar units. The unit is no longer available from Chevrolet, but Stealth Conversions has a large inventory of the remaining units. This will work for a 1990-1992 TPI (or 1990-1992 Camaro V6) and 1992-1993 LT1 engine with a 700-R4 transmission or ZF six-speed into a vehicle which requires a mechanical speedometer. This unit comes in two styles: one for 34-39 tooth driven gears, and one for 40-45 tooth driven gears. They use the same speedometer gears as the Corvettes and Camaros. This unit will also trigger the 4-output vehicle speed buffer shown on page 12-2 of the VSS chapter. This unit is made of plastic, and will not support an angle drive unit.

The picture above gives a closer view of the stock sensor (GM part # 15547452), used on 1989 and newer 4X4 trucks. It is shown with the wiring connector, or "pigtail" (an aftermarket part, equivalent to GM part # 12085498), and compared to the modified speed sensor. You can modify the speed sensor yourself if you are good with a soldering iron.

NEW Toyota FJ-40 reluctor ring kit

This kit bolts to rear of the transfer case, and provides the proper vss signal for the 1993 and newer Chevrolet engine. Kit includes vss, reluctor ring, and rear cover assembly.